Bru'n water issue (low pH prediction, distilled water)

[max_the_hop]

I am having troubles with the Bru'n Water software. I have used it maybe 6 times and every time I haved failed to hit the mash pH the software predicted. The mash pH prediction is always lower that what I measure with my pH meter. For example, my last brew I missed my pH by .16 points (5.36 predicted pH but meter reading of 5.52 at 30 mins in mash). The brew before by .13 points (5.27 predicted pH but meter reading of 5.40 at 30 mins in mash)... I understand these pH readings are not that bad, especially the latter, but I am aiming for precision!

To nail my pH I have only been using salts. I stir them in thoroughly. I also am careful in taking my measurements and I am sure my pH meter is well calibrated (I have two different meters and both meters give me the same reading). I am aware that some brands of grain buffers differently. I only use Canada Malting 2-row along side with some crystal, honey malt, carapils and malted wheat.

I also use 100% distilled water and therefore have my water profile set to 0 and to a pH of 7. I am pretty sure the distilled water is good. I buy it from a store that specializes in distilled water. That is all it sells.

if possible, could anybody that knows the software well take a quick look at my excel sheets from my two last brews to troubleshoot my problem? Maybe I am missing a variable. I don't think so but it is possible.

 

[ajdelange]

It is, of course, possible that you are making data entry errors but I believe the fundamental problem is that you are asking too much of the software. It relies on a model of malt titratable acidity that is based mostly on color. Color is not really a good predictor of this (but it's not that bad either hence your ability to get predictions as good as the ones you do). I very much doubt that Canada Malting 2-row was included in the development of the model.

From reports I have seen here I believe that Bru'n water does tend to undershoot. To correct for this you might try telling the program that your base malt is paler (smaller Lovibond rating) that it actually is. This should fool it into thinking that your malt is less acidic and might give you pH prediction results closer to what you are seeing. Of course you should verify that your pH readings are solid. See https://www.homebrewtalk.com/showthread.php?t=302256